Turbo Noise

[dilbert3703]

Here’s a question for those of you familiar with the 2005 Powerstroke. When I accelerate fairly hard and release the accelerator pedal suddenly, I sometimes hear a gurgling sound. Okay, that's not a good description. It sort of reminds me of the sound you get when you accelarate a gasser hard and the back off, but it doesn't last but a moment.

The sound usually occurs when I suddenly release the accelerator, but when towing our fifth-wheel trailer home last Saturday, I heard the gurgling sound briefly when the transmission shifted. We were going up a slight hill and the transmission was shifting into a higher gear. In the pause between gears, when the RPMs dropped, I heard the gurgling sound briefly.

I think the noise is coming from the turbo, but I’m looking for confirmation from those who have experience. I understand these turbos don’t have wastegate, so what’s happening to cause the noise? And, more importantly, is it a problem?

Thanks in advance for you feedback.

 

[stroker21]

It sounds like what I hear more promenant on manual trans when they are accelerating hard then let off and it kind of whistles(is the way I would have to describe it). I hear it a lot more on the cummins with straight pipes. The manual PSDs do it as well when shifting I just see more cummins with manuals.

 

[Kleetus]

Turbo Fart...

This is normal. What it boils down to is under load the compressor and turbine are balanced force wise, that is, exhaust pressure is such that it's spinning the compressor to make whatever boost level you're at. You dump off the fuel or it shifts and backs off some, the exhaust pressure is no longer sufficient to keep the compressor spinning at it's current speed and pressure load. Now the compressed air in the intake pushes back to atmosphere, and momentarily makes a very drastic speed change in the compressor wheel, it might stop or even backspin some until the flows equalize and the turbo comes back to equilibrium and operates in a normal fashion.

What you're hearing is the air and exhaust gases running around the blades in a less than controlled manner. It's probably not the best thing for a turbo, just from a stress standpoint, but I really don't think it would kill it.

 

[lvtitan]

it is compresser surge, from not having a blowoff valve. not from not having a wastegate... it is not really good for the turbo, so try to avoid doing it, release the throttle smoothly if you are under hard acceleration, or add a blowoff valve.

 

[dilbert3703]

Ivtitan:

Thanks for the reply. Please tell me more about adding a blowoff valve. Who makes them, how they are installed, etc.

Thanks again.

 

[DaveBen]

You can't really add a blow off valve, as your turbo charger has variable vanes to regulate the boost pressure. Don't mess with this, just adjust your driving style. I have never had a turbo fart.

Dave

 

[DragonSlayer]

Its like the others said, just try not to do it alot and you'll be fine.

 

[lvtitan]

You can't really add a blow off valve, as your turbo charger has variable vanes to regulate the boost pressure. Don't mess with this, just adjust your driving style. I have never had a turbo fart.

Dave

first of all, a blowoff valve has NOTHING to do with regulating boost pressure. it relieves compressor surge on the intake side of the equation.
and every one of our race cars uses them (gasoline motors) but they are just as effective on diesel. if you have constant compressor surge you can damage your turbo.
i am not running one on mine, but i ease off of the throttle to avoid it.

a blowoff valve is installed before the intake manifold on the intercooler piping and is normally closed during boost, when you let off the throttle it opens up, bypassing the compressed air in the i/c piping into the atmosphere instead of back into the compressor wheel.